A passenger conveyor is provided with a missing step detection device. This missing step detection device is intended for preventing a passenger conveyor from coming into an ordinary operating state, with the step removed for maintenance and for other purposes kept unattached after the completion of the maintenance. Conventional missing step detection devices have detected a missing condition of steps by pressing a roller against the steps and sensing positional changes of the roller. In these missing step detection devices, the wear of the roller has a great effect on the life of the devices. However, passenger conveyors are constantly continuing operations. For this reason, even when the durability of the roller is increased, there has been a limit to the life extending of missing step detection devices.
Therefore, there has been proposed a missing step detection device which measures the dimension of the clearance between adjacent steps in a noncontact manner by use of an induction proximity detector and judges that there is a missing condition of steps when this dimension of the clearance is larger than a threshold value. This missing step detection device uses no roller. This enables the life of the missing step detection device to be extended (refer to Patent Document 1, for example).
Patent Document 1: Japanese Patent Laid-Open No. 6-211480